T1 L3: Blood volume and its regulation by the kidney

• What components of blood are central to blood volume setting in the kidney?

  sodium, water
• Formed elements (RBCs, WBCs, plasma) do not contribute directly to blood pressure.
• Three ways to increase blood pressure?

  1. high blood volume
  2. vasoconstriction
  3. high cardiac output
• Fluid entering all Bowman's capsules?

  Glomerular Filtration Rate
• Diagnostic tests for kidney function?

  1. Blood urea nitrogen (BUN)
  2. Serum creatinine
  3. B-type natriuretic peptide (BNP)
• Which test measures urea, waste product of protein digestion, produced by the liver, and hence measuring if it is removed correctly by the kidneys?

  blood urea nitrogen (BUN)
• What is high BUN caused by?

  low GFR
• Along with low GFR, what can high BUN levels indicate?

  kidney failure, CHF, hypovolaemia
• What do high levels of serum creatinine indicate?

  low GFR
• Which hormone directly decreases diuresis?

  Antidiuretic hormone (ADH, vasopressin)
• What is ADH secreted from?

  posterior pituitary gland
• Effect of decreased diuresis on blood pressure?

  increased blood pressure
• What is loss of plasma fluid into urine called?

  diuresis
• How do diuretic drugs work?

  antagonise antidiuretic hormones, leading to fluid loss
• Steroid hormone that increases plasma fluid?

  aldosterone
• What kind of hormone is aldosterone?

  mineralocorticoid
• What is aldosterone secreted by?

  adrenal cortex
• How does aldosterone increase plasma fluid?

  aldosterone ➝ kidneys ➝ reabsorb more NaCl ➝ water follows salt ➝ reabsorb more water ➝ decrease diuresis by decreasing natriuresis
• Hormone that increases blood pressure?

  angiotensin II
• How does angiotensin increase blood pressure?

  • causes vasoconstriction
  • increases fluid retention by:
  • increasing aldosterone secretion by adrenal cortex (more blood volume)
  • increasing ADH secretion by posterior pituitary (antidiuretic)
• Hormone that contributes to ventricular hypertrophy + cardiac remodelling?

  angiotensin II
• What system regulates blood pressure and volume?

  Renin-Angiotensin-Aldosterone System (RAAS)
• Renin-Angiotensin-Aldosterone System mechanism?

  angiotensinogen produced by liver ➝ activated by RENIN enzyme (made in kidneys) ➝ becomes angiotensin I ➝ activated by ACE enzyme (made in lungs) ➝ becomes angiotensin II ➝ activates aldosterone
• Cytokine/hormone that derives erythropoiesis?

  Erythropoietin (EPO)
• Where is EPO made?

  kidney
• What is EPO made in the liver in response to?

  hypoxia in kidney
• What peptide hormone reduces fluid overload?

  B-type Natriuretic Peptide (BNP)
• What is B-type Natriuretic Peptide (BNP) secreted by?

  ventricular cardiomyocytes
• What is B-type Natriuretic Peptide (BNP) secreted in response to?

  increased preload (diastolic stretching) and volume overload
• How does B-type Natriuretic Peptide (BNP) work?

  increases natriuresis ➝ increased GFR ➝ increase diuresis ➝ decrease venous pressure and systemic peripheral vascular resistance
• Elevated levels of which hormone indicates heart failure?

  B-type Natriuretic Peptide (BNP)
• What does congestion inside hepatic portal system cause?

  ascites
• Fluid build up in abdomen?

  ascites
• 2 ways kidney acid-base balance fails?

  • kidney failure (glomerulus doesn't filter)
  • renal tubular failure (tubules don't get rid of acid)
• Low GFR, high creatinine & BUN, metabolic acidosis, high anion gap, high BP, low urine, oedema, need to urinate more esp at night?

  Acute kidney injury / uremic kidney failure
• Normal GFR, metabolic acidosis, normal anion gap, low blood K+, non-anion gap hyperchloremic metabolic acidosis?

  Renal tubule failure
• Example of thiazide like diuretic?

  indapamide
• Type of diuretics that work by blocking reabsorption at DCT?

  thiazide like
• Type of diuretics that work by blocking reabsorption in thick loop?

  loop
• Example of a loop diuretic?

  furosemide